Microchip AT24C02C-XHM-B: A Deep Dive into the 2-Wire Serial EEPROM Memory Chip
In the realm of embedded systems and IoT devices, the need for reliable, non-volatile memory for storing configuration data, calibration constants, or event logs is paramount. The Microchip AT24C02C-XHM-B stands as a robust and efficient solution, offering 2 Kbits of serial Electrically Erasable Programmable Read-Only Memory (EEPROM) accessible via a simple 2-wire serial interface. This memory chip is engineered for low-power operation and high reliability, making it an ideal choice for a vast array of consumer, industrial, and automotive applications.
Key Features and Datasheet Highlights
The AT24C02C-XHM-B is part of Microchip's extensive family of serial EEPROMs. Its operation is centered on the ubiquitous I²C (Inter-Integrated Circuit) protocol, which requires only two bidirectional open-drain lines: Serial Data (SDA) and Serial Clock (SCL). This drastically reduces the number of GPIO pins required on a host microcontroller, simplifying board layout and design.
According to its datasheet, the device is organized as 256 x 8 (2 Kbit). Key electrical characteristics underscore its suitability for modern, power-sensitive designs:
Low Voltage Operation: It supports a wide voltage range from 1.7V to 5.5V, enabling compatibility with both older 5V systems and contemporary 1.8V or 3.3V microcontrollers.
Low Power Consumption: The chip features a standby current of just 1 µA (max at 1.7V) and an active read current of 0.04 mA (at 100 kHz, 1.7V), which is critical for battery-powered applications.
High Reliability: It is endurance tested for 1,000,000 erase/write cycles per byte and boasts a data retention period of 100 years, ensuring data integrity over the product's lifetime.
Page Write Capability: The memory is configured in a 16-byte page structure, allowing for faster write operations by writing multiple bytes in a single protocol sequence.
Noise Immunity: Integrated Schmitt triggers and input filters on the SDA and SCL lines enhance noise immunity, ensuring stable communication in electrically noisy environments.
Practical Application Notes
Implementing the AT24C02C in a design is straightforward, but several best practices highlighted in the application notes are crucial for optimal performance.
1. Hardware Connection: The I²C bus requires pull-up resistors on both the SDA and SCL lines. The value of these resistors (typically between 2.2kΩ and 10kΩ) depends on the bus speed and the total capacitive load on the lines. The device address pins (A0, A1, A2) allow for up to eight identical devices to be connected on the same bus, providing addressability for a total of 16 Kbits of memory.
2. Write Cycle Timing: After issuing a write command (either byte or page write), the device initiates an internal timed write cycle (tWR) to program the non-volatile memory cells. During this period, which lasts a maximum of 5 ms, the chip will not acknowledge its address (a process known as polling). The host microcontroller must wait for this cycle to complete before sending the next command.
3. Software Protocol: The communication driver on the MCU must correctly generate:
START and STOP conditions to initiate and terminate transactions.
Acknowledge bits after each byte transfer.
The correct device address byte, including the R/W bit, to target the specific EEPROM for read or write operations.
4. PCB Layout: To minimize noise coupling, it is advised to keep the I²C trace lengths as short as possible and avoid running them parallel to high-speed or noisy signals like clock lines.
ICGOOODFIND
The Microchip AT24C02C-XHM-B is a quintessential component for designers seeking a simple, reliable, and low-power method for adding non-volatile memory. Its industry-standard I²C interface, combined with exceptional endurance and retention specifications, makes it a versatile and trustworthy choice for everything from smart home sensors and wearables to complex industrial controllers. By adhering to the application guidelines for hardware design and communication protocol management, engineers can seamlessly integrate this EEPROM to ensure robust and dependable data storage.
Keywords:
I²C Interface
Non-Volatile Memory
Low-Power Consumption
Data Retention
Page Write
